1 Field of the Invention
The invention relates to a method for setting priority levels in a multiprogramming computer system with priority scheduling, to a multiprogramming computer system with priority scheduling, and to a computer program loadable onto a multiprogramming computer system with priority scheduling.
2 Description of Related Art
A multiprogramming computer system is a computer system that is able to switch back and forth between multiple programs loaded in memory. The operating system of such a computer comprises a scheduler, a part that chooses which of two or more threads of execution that are ready to run should be run next. To ensure that certain threads are more likely to be chosen than others, threads have a priority level assigned to them.
Although common operating systems have mechanisms for changing priority levels, the basic setting of the priority level for processes and/or threads that are created when an application program is run, is not carried out by the operating system. Either the level is set by the provider of an application program, or it is set by a system administrator. This can lead to problems when the execution of a certain program requires a large amount of processor capacity. The high priority setting will lead to a situation where the thread or threads of execution of this program consume all of the available processing resources. This is detrimental to the performance of other processes simultaneously running on the computer system. In situations where different users run application programs on one system, a process started by one of them can cause the other processes to respond very slowly to commands entered by another user.